Question on thread tension on machine quilting

Can any of you quilters tell me why sometimes when a quilt is done on a professional long arm machine why the tension comes back wrong on parts of the quilt? Is this a hard thing to control? This quilt shop has a tension regulator on this machine. Thanks.

Sometimes a different fabric on the top can mess up the tension on the back. If you mix regular quilting cotton with batiks, they will quilt differently. Sometimes if there are a lot of seam allowances that the machine goes over it can throw off the tension too.

They probably have a Towa Bobbin tensioner. This sets the tension on a bobbin, but when it's off the machine. If different parts of the quilt are pieced with different fabrics or lots more piecing in one area than another, then this can throw the tension off. If there's no fabric differences, then is the tension off on just curves? This might mean that they are going too fast on them. With some stitch regulators, you still can't go from zero to 60. May need to slow down on some of the curves.
I agree with Peckish about taking the quilt back to the long armer and asking.

"I do not understand how anyone can live without one small place of enchantment to turn to."
Marjorie Kinnan Rawlings

I meant to say stitch regulator, instead of tension regulator.
This particular quilt (that I picked up yesterday from the quilting shop after it was quilted) was very simple piecing.
It was a baby quilt, and basically it had one large center piece with a border of a different color, and on the back the colors were reversed---large center piece and border on the side. It was machine quilted all over with the same pattern, circle with stars in the middle. For some reason, the stitching was off on the brown fabric much more consistently than the pink fabric. I have seen this on some other quilts that I have had professionally quilted, and I hoped that I can get this resolved for the future. Didn't know if it was the patterns I was choosing, or the speed the long arm quilter was using, and something else. Do any of you have this issue very often? Thank you for your suggestions. PaperPrincess, you commented this sets the tension on the bobbin, but when it's off the machine. I am not sure what you meant by the last part of the sentence. Thanks.

The stitches are off are on the back; they are on straight seams and curves. This particular machine quilting pattern does have a lot of curves because of all the circles. Thanks again for any advice you have for me.

She means the tension is set in the bobbin case when the bobbin is not inside the machine. The bobbin and bobbin case are taken out of the machine and set into the gauge. Once the tension is read and set, the bobbin and case are put back into the machine. I personally don't think this has anything to do with what's going on with your quilt.

I have a few questions: Is the brown fabric a batik? You say this has happened before on other quilts, was it the same longarm quilter? Did you show her those quilts and ask about the problem? Can you post a picture of the problem areas?

I forgot to say both the brown and pink are 100% cotton fabric.
Can a thicker or thinner batting have anything to do with the tension issue?
Usually I have the long arm quilter use Quilters Dream Cotton Select, and occasionally I have use that same brand in Deluxe (which is a little thicker). This particular time that the tension was off was on the select.

Peckish,
The brown fabric was not a batik. It is the same longarm quilter. I have mentioned this problem to her before. She wasn't sure what caused it---thinking maybe it was the pattern. I am not sure how to post a picture. Can you tell me how? Thanks.

There's a couple of ways to post a picture. This is the easiest way - see if you can click and drag the picture into your dialogue box where you type responses. Make sure the picture is 1 mb or smaller.